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1.
Takuya Kajimoto 《Ecological Research》1989,4(1):55-69
Aboveground biomass and litterfall ofPinus pumila scrubs, growing on the Kiso mountain range in central Japan, were investigated from 1984 to 1985. The biomass of two research
plots (P1 and P2) with different scrub heights was estimated by two methods, the stratified clip technique and the allometric
method. Aboveground total biomass estimated by the latter method reached 181 ton d.w. ha−1 in P1 and 132 ton d.w. ha−1 in P2. Creeping stems contributed to about half of the total biomass. Although estimates of woody organs differed between
the two plots, leaf biomass estimates were almost the same at 15.5 ton d.w. ha−1. The canopies of the twoP. pumila scrubs were characterized by a large mean leaf area density of 5.0 m2 m−3. Despite this large area density, relatively moderate attenuation of light intensity was observed. Specific leaf area generally
increased with reduced leaf height. Annual total litterfall was estimated to be 3.60 ton d.w. ha−1 yr−1 in P1 and 2.39 ton d.w. ha−1 yr−1 in P2. Annual leaf fall in both plots was approximately 2.0 ton d.w. ha−1 yr−1. Leaves fell mainly in early autumn. Annual loss rates of branches, estimated as the sum of annual branch litterfall and
the amount of newly formed attached dead branches, were 0.29 ton d.w. ha−1 yr−1 in P1 and 0.37 ton d.w. ha−1 yr−1 in P2. 相似文献
2.
Biomass and net production were measured in aPhyllostachys bambusoides stand in Kyoto Prefecture, central Japan, which had carried out gregarious flowering in 1969 and has been recovering vegetatively.
The culm density fluctuated around an average value of 12 040 ha−1 during the research period (1985–91). Annual recruirment and mortality rates of culms were 1340 and 1133 ha−1, respectively. The mean diameter at breast height increased from 7.28 cm in 1985 to 8.68 cm in 1991, and the biomass of culms
increased from 71.3 to 111.6t ha−1 over the same time period. Branch and leaf biomasses were almost constant, 10.0 and 9.4t ha−1 on average, respectively. The leaf area index of the stand was 11.6 ha ha−1, which is one of the largest values found in Japanese forests. The belowground biomass of 32.6t ha−1 for rhizomes and 14.8t ha−1 for fine roots resulted in the smaller ratio of aboveground parts to the root system (2.38) than those determined for forest
stands. The amount of litterfall, excluding culms and large branches, was large (9.13t ha−1 year−1), corresponding to those measured in equatorial stands. The aboveground net production was 24.6t ha−1 year−1, larger than the average value reported for forest stands under similar weather conditions. 相似文献
3.
Byung Bae Park Ruth D. Yanai Timothy J. Fahey Scott W. Bailey Thomas G. Siccama James B. Shanley Natalie L. Cleavitt 《Ecosystems》2008,11(2):325-341
Losses of soil base cations due to acid rain have been implicated in declines of red spruce and sugar maple in the northeastern
USA. We studied fine root and aboveground biomass and production in five northern hardwood and three conifer stands differing
in soil Ca status at Sleepers River, VT; Hubbard Brook, NH; and Cone Pond, NH. Neither aboveground biomass and production
nor belowground biomass were related to soil Ca or Ca:Al ratios across this gradient. Hardwood stands had 37% higher aboveground
biomass (P = 0.03) and 44% higher leaf litter production (P < 0.01) than the conifer stands, on average. Fine root biomass (<2 mm in diameter) in the upper 35 cm of the soil, including
the forest floor, was very similar in hardwoods and conifers (5.92 and 5.93 Mg ha−1). The turnover coefficient (TC) of fine roots smaller than 1 mm ranged from 0.62 to 1.86 y−1 and increased significantly with soil exchangeable Ca (P = 0.03). As a result, calculated fine root production was clearly higher in sites with higher soil Ca (P = 0.02). Fine root production (biomass times turnover) ranged from 1.2 to 3.7 Mg ha−1 y−1 for hardwood stands and from 0.9 to 2.3 Mg ha−1 y−1 for conifer stands. The relationship we observed between soil Ca availability and root production suggests that cation depletion
might lead to reduced carbon allocation to roots in these ecosystems. 相似文献
4.
Yuji Isagi 《Ecological Research》1994,9(1):47-55
Gross production and carbon cycling in aPhyllostachys bambusoides stand in Kyoto Prefecture, central Japan, were determined, and then a compartment model showing the carbon stock and cycling
within the ecosystem was developed. Aboveground carbon stock was 52.3 tC ha−1, increasing at a rate of 3.6 tC ha−1 year−1. Belowground carbon stock was 20.8 tC ha−1 in the root system and 92.0 tC ha−1 in the soil. Aboveground net production was 11.2 tC ha−1 year−1. Belowground net production was crudely estimated at 4.5 tC ha−1 year−1. The gross production was estimated at 41.8 tC ha−1 year−1 by summing the amount of outflow to the environment and the increment in biomass. Leaves consumed 13.7 tC ha−1 year−1 by respiration; the rest (41.8−13.7=28.1 tC ha−1 year−1) was surplus production of the leaves and flowed into the other compartments. The amounts of construction and maintenance
respiration of the aboveground compartments were 3.4 and 18.5 tC ha−1 year−1, respectively. The annual amount of soil respiration was 11.2 tC ha−1 year−1. Soil respiration levels of 4.3 and 3.1 tC ha−1 year−1 were estimated for the flow of root respiration and root detritus. The proportion of net to gross production was 37%, which
fell within the range of young and mature forests. A shorter life span of culms, compared to tree trunks, resulted in smaller
biomass accumulation ratio (biomass/net production) in the ecosystem, of 4.66. 相似文献
5.
Aboveground net primary production (ANPP) and leaf-area index (LAI) of lodgepole pine (Pinus contorta var. latifolia Engelm. ex Wats.) saplings and aboveground productivity of herbaceous vegetation components were determined 9 years after
the 1988 fires in Yellowstone National Park (YNP). Measurements were made in four sites representing a wide range of early
postfire vegetation present in YNP, including high-density lodgepole pine, low-density lodgepole pine, and two nonforest stands.
LAI of the pine saplings and total ANPP (trees plus herbs) generally increased with increasing sapling density, from 0.002
m2 m−
2 and 0.25 Mg ha−
1 year−
1 in the infertile nonforest stand (100 pine saplings ha−
1) to 1.8 m2 m−
2 and 4.01 Mg ha−
1 year−
1 in the high-density pine stand (62,800 saplings ha−
1). Aboveground herbaceous productivity was not strongly correlated with sapling density, but appeared to be influenced by
soil fertility. In the high-density pine stand, tree ANPP and LAI were within the lower range of values reported for similar
mature coniferous forests. This finding suggests that at least some ecosystem processes (related to ANPP and LAI) may have
nearly recovered after only 9 years of postfire succession, in at least some of the young forests developing after the 1988
Yellowstone fires.
Received 7 April 1998; accepted 1 December 1998. 相似文献
6.
Estimates of biomass and primary productivity in a high-altitude maple forest of the west central Himalayas 总被引:4,自引:0,他引:4
S. C. Garkoti 《Ecological Research》2008,23(1):41-49
The paper describes the biomass and productivity of maple (Acer cappadocicum) forest occurring at an altitude of 2,750 m in the west central Himalayas. Total vegetation biomass was 308.3 t ha−1, of which the tree layer contributed the most, followed by herbs and shrubs. The seasonal forest-floor litter mass varied
between 5.4 t ha−1 (in rainy season) and 6.6 t ha−1 (in winter season). The annual litter fall was 6.2 t ha−1, of which leaf litter contributed the largest part (59% of the total litter fall). Net primary productivity of total vegetation
was 19.5 t ha−1 year−1. The production efficiency of leaves (net primary productivity/leaf mass) was markedly higher (2.9 g g−1 foliage mass year−1) than those of the low-altitude forests of the region. 相似文献
7.
The dynamics of aboveground big woody organs over 10 cm diameter was studied at a mature foothill dipterocarp forest in West
Sumatra. The biomass of big woody organs was estimated to be 519 m3 ha−1 or 408 metric ton ha−1 by means of a pipe model theory. The diameter distribution showed a convex curve and the mode was found at a diameter of
about 20 cm. The standing mass of big dead woody litter on the forest floor was 116 m3 ha−1, which accounted for 22% by voume or 9.5% by weight of the biomass of living organs respectively. Thedbh observation with two 1-ha plots for 4 yr and 5 yr respectively revealed that the average net production rate was 9.5 ton
ha−1 yr−1. The death rate (7.9 ton ha−1 yr−1) accounted for 83% of the net production rate and was nearly equivalent to the decay rate (7.5 ha−1 yr−1) of dead wood on the forest floor. The balance between the death and decay rates was confirmed for each diameter class. Average
turnover periods for big woody organs and dead woody litter were estimated to be 43 and 8.1 yr, respectively. Standing masses
of live anddead woody materials accumulated in the study forest were approximately equal to those obtained in a mature tropical
lowland rainforest, whereas the flow rates were lower, being only 70% of the corresponding values. 相似文献
8.
Above- and belowground organic matter storage and production in a tropical pine plantation and a paired broadleaf secondary forest 总被引:7,自引:1,他引:6
The distribution of tree biomass and the allocation of organic matter production were measured in an 11-yr-old Pinus caribaea plantation and a paired broadleaf secondary forest growing under the same climatic conditions. The pine plantation had significantly
more mass aboveground than the secondary forest (94.9 vs 35.6 t ha-1 for biomass and 10.5 vs 5.0 t ha-1 for litter), whereas the secondary forest had significantly more fine roots (⩽2 mm diameter) than the pine plantation (10.5 and 1.0
t ha-1, respectively). Standing stock of dead fine roots was higher than aboveground litter in the secondary forest. In contrast,
aboveground litter in pine was more than ten times higher than the dead root fraction. Both pine and secondary forests had
similar total organic matter productions (19.2 and 19.4 t ha-1 yr-1, respectively) but structural allocation of that production was significantly different between the two forests; 44% of total
production was allocated belowground in the secondary forest, whereas 94% was allocated aboveground in pine. The growth strategies
represented by fast growth and large structural allocation aboveground, as for pine, and almost half the production allocated
belowground, as for the secondary forest, illustrate equally successful, but contrasting growth strategies under the same
climate, regardless of soil characteristics. The patterns of accumulation of organic matter in the soil profile indicated
contrasting nutrient immobilization and mineralization sites and sources for soil organic matter formation. 相似文献
9.
Soil respiration and carbon balance in a subtropical native forest and two managed plantations 总被引:3,自引:0,他引:3
Yu-Sheng Yang Guang-Shui Chen Jian-Fen Guo Jin-Sheng Xie Xiao-Guo Wang 《Plant Ecology》2007,192(1):71-84
From 1999 to 2003, a range of carbon fluxes was measured and integrated to establish a carbon balance for a natural evergreen
forest of Castanopsis kawakamii (NF) and adjacent monoculture evergreen plantations of C. kawakamii (CK) and Chinese fir (Cunninghamia lanceolata, CF) in Sanming Nature Reserve, Fujian, China. Biomass carbon increment of aboveground parts and coarse roots were measured
by the allometric method. Above- and belowground litter C inputs were assessed by litter traps and sequential cores, respectively.
Soil respiration (SR) was determined by the alkaline absorbance method, and the contribution from roots, above- and belowground litters was separated
by the DIRT plots. Annual SR averaged 13.742 t C ha−1 a−1 in the NF, 9.439 t C ha−1 a−1 in the CK, and 4.543 t C ha−1 a−1 in the CF. For all forests, SR generally peaked in later spring or early summer (May or June). The contribution of root respiration ranged from 47.8% in
the NF to 40.3% in the CF. On average, soil heterotrophic respiration (HR) was evenly distributed between below- (47.3∼54.5%) and aboveground litter (45.5%–52.7%). Annual C inputs (t C ha−1 a−1) from litterfall and root turnover averaged 4.452 and 4.295, 4.548 and 2.313, and 2.220 and 1.265, respectively, in the NF,
CK, and CF. As compared to HR, annual net primary production (NPP) of 11.228, 13.264, and 6.491 t C ha−1 a−1 in the NF, CK, and CF brought a positive net ecosystem production (NEP) of 4.144, 7.514, and 3.677 t C ha−1 a−1, respectively. It suggests that native forest in subtropical China currently acts as an important carbon sink just as the
timber plantation does, and converting native forest to tree plantations locally during last decades might have caused a high
landscape carbon loss to the atmosphere. 相似文献
10.
Differential Snowpack Accumulation and Water Dynamics in Aspen and Conifer Communities: Implications for Water Yield and Ecosystem Function 总被引:2,自引:0,他引:2
Early succession aspen and late succession conifer forests have different architecture and physiology affecting hydrologic
transfer processes. An evaluation of water pools and fluxes was used to determine differences in the hydrologic dynamics between
stands of quaking aspen (Populus tremuloides) and associated stands of mixed conifer consisting of white fir (Abies concolor), Douglas-fir (Pseudotsuga menziesii), and Engelmann spruce (Picea engelmannii). In 2005 and 2006, measurements of snow water accumulation, snow ablation (melt), soil water content, snowpack sublimation,
and evapotranspiration (ET) were measured in adjacent aspen and conifer stands. Peak snow water equivalent (SWE) averaged
34–44% higher in aspen in 2005 (average snow fall) and 2006 (above average snow fall), respectively, whereas snow ablation
rates were greater in aspen stands (21 mm day−1) compared to conifer stands (11 mm day−1). When changes in soil water content (due to over-winter snowmelt) were combined with peak snow accumulation in 2006, aspen
had greater potential (42–83%) water yield for runoff and groundwater recharge. Snowpack sublimation during the ablation period
was not significantly different between meadow, aspen, and conifer sites and comprised less than 5% of the winter precipitation.
Extended conifer transpiration in spring and fall did not contribute to large differences in water yield (<28 mm y−1). Summertime ET rates were higher in aspen plots (3.6 mm day−1) than in conifer plots (2.7 mm day−1), and differences in net ET largely reflected soil column porosity. This study shows that the largest differences in annual
water yield between aspen and conifer stands result from differences in SWE and net summertime ET. Although SWE and accumulation
of water in soil was greater in aspen, it was partly offset by greater net annual ET losses in aspen. 相似文献
11.
Yuichiro Yashiro Na-Yeon M. Lee Toshiyuki Ohtsuka Yoko Shizu Taku M. Saitoh Hiroshi Koizumi 《Journal of plant research》2010,123(4):463-472
Quantification of carbon budgets and cycling in Japanese cedar (Cryptomeria japonica D. Don) plantations is essential for understanding forest functions in Japan because these plantations occupy about 20% of
the total forested area. We conducted a biometric estimate of net ecosystem production (NEP) in a mature Japanese cedar plantation
beneath a flux tower over a 4-year period. Net primary production (NPP) was 7.9 Mg C ha−1 year−1 and consisted mainly of tree biomass increment and aboveground litter production. Respiration was calculated as 6.8 (soil)
and 3.3 (root) Mg C ha−1 year−1. Thus, NEP in the plantation was 4.3 Mg C ha−1 year−1. In agreement with the tower-based flux findings, this result suggests that the Japanese cedar plantation was a strong carbon
sink. The biometric-based NEP was higher among most other types of Japanese forests studied. Carbon sequestration in the mature
plantation was characterized by a larger increment in tree biomass and lower mortality than in natural forests. Land-use change
from natural forest to Japanese cedar plantation might, therefore, stimulate carbon sequestration and change the carbon allocation
of NPP from an increment in coarse woody debris to an increase in tree biomass. 相似文献
12.
Naoki Hijii 《Ecological Research》1994,9(2):175-183
Seasonal changes in abundances of major soil micro-arthropods were assessed at aPinus pumila scrub in an alpine range of central Japan during a period with no snow coverage. The total abundance showed a peak in late
August, reaching no less than 140 000 m−2, which was comparable to that in an evergreen coniferous plantation in the cool-temperate zone. Collembola was the most dominant
group of soil micro-arthropods, comprising about 50% of the total, followed by oribatid mites (Acari [O]) occupying 20%. Annual
mean air temperature was no more than 2.1 °C and the daily fluctuation in temperature was less in soil layers. The thickness
of the A0 layer reached 9–10 cm and soil organic matter accumulation was estimated to be 45–58 ton dry weight ha−1. The large amount of litterfall and organic matter accumulation in the soil, comparable to those of sub-alpine evergreen
coniferous forests, and a lower decomposition rate due to severe environmental conditions, suggest the relative importance
of litter processing by soil micro-arthropods such as Collembola and Acari, especially in alpine regions. 相似文献
13.
We investigated the influence of the exotic nitrogen-fixing black locust (Robinia pseudoacacia) on nitrogen cycling in a pitch pine (Pinus rigida) −scrub oak (Quercus ilicifolia, Q. prinoides) ecosystem. Within paired pine-oak and adjacent black locust stands that were the result of a 20-35 year-old invasion, we
evaluated soil nutrient contents, soil nitrogen transformation rates, and annual litterfall biomass and nitrogen concentrations.
In the A horizon, black locust soils had 1.3-3.2 times greater nitrogen concentration relative to soils within pine-oak stands.
Black locust soils also had elevated levels of P and Ca, net nitrification rates and total net N-mineralization rates. Net
nitrification rates were 25-120 times greater in black locust than in pine-oak stands. Elevated net N-mineralization rates
in black locust stands were associated with an abundance of high nitrogen, low lignin leaf litter, with 86 kg N ha–1 yr–1 in leaf litter returned compared with 19 kg N ha–1 yr–1 in pine-oak stands. This difference resulted from a two-fold greater litterfall mass combined with increased litter nitrogen
concentration in black locust stands (1.1% and 2.6% N for scrub oak and black locust litter, respectively). Thus, black locust
supplements soil nitrogen pools, increases nitrogen return in litterfall, and enhances soil nitrogen mineralization rates
when it invades nutrient poor, pine-oak ecosystems.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
14.
Eva Ritter 《Plant and Soil》2007,295(1-2):239-251
Afforestation has become an important tool for soil protection and land reclamation in Iceland. Nevertheless, the harsh climate
and degraded soils are growth-limiting for trees, and little is know about changes in soil nutrients in maturing forests planted
on the volcanic soils. In the present chronosequence study, changes in C, N and total P in soil (0–10 and 10–20 cm depth)
and C and N in foliar tissue were investigated in stands of native Downy birch (Betula pubescens Enrh.) and the in Iceland introduced Siberian larch (Larix sibirica Ledeb.). The forest stands were between 14 and 97 years old and were established on heath land that had been treeless for
centuries. Soils were Andosols derived from basaltic material and rhyolitic volcanic ash. A significant effect of tree species
was only found for the N content in foliar tissue. Foliar N concentrations were significantly higher and foliar C/N ratios
significantly lower in larch needles than in birch leaves. There was no effect of stand age. Changes in soil C and the soil
nutrient status with time after afforestation were little significant. Soil C concentrations in 0–10 cm depth in forest stands
older than 30 years were significantly higher than in heath land and forest stands younger than 30 years. This was attributed
to a slow accumulation of organic matter. Soil N concentrations and soil Ptot were not affected by stand age. Nutrient pools in the two soil layers were calculated for an average weight of soil material
(400 Mg soil ha−1 in 0–10 cm depth and 600 Mg soil ha−1 in 10–20 cm depth, respectively). Soil nutrient pools did not change significantly with time. Soil C pools were in average
23.6 Mg ha−1 in the upper soil layer and 16.9 Mg ha−1 in the lower soil layer. The highest annual increase in soil C under forest compared to heath land was 0.23 Mg C ha−1 year−1 in 0–10 cm depth calculated for the 53-year-old larch stand. Soil N pools were in average 1.0 Mg N ha−1 in both soil layers and did not decrease with time despite a low N deposition and the uptake and accumulation of N in biomass
of the growing trees. Soil Ptot pools were in average 220 and 320 kg P ha−1 in the upper and lower soil layer, respectively. It was assumed that mycorrhizal fungi present in the stands had an influence
on the availability of N and P to the trees.
Responsible Editor: Hans Lambers. 相似文献
15.
Toshiyuki Ohtsuka Wenhong Mo Takami Satomura Motoko Inatomi Hiroshi Koizumi 《Ecosystems》2007,10(2):324-334
Biometric based carbon flux measurements were conducted over 5 years (1999–2003) in a temperate deciduous broad-leaved forest
of the AsiaFlux network to estimate net ecosystem production (NEP). Biometric based NEP, as measured by the balance between
net primary production (including NPP of canopy trees and of forest floor dwarf bamboo) and heterotrophic respiration (RH),
clarified the contribution of various biological processes to the ecosystem carbon budget, and also showed where and how the
forest is storing C. The mean NPP of the trees was 5.4 ± 1.07 t C ha−1 y−1, including biomass increment (0.3 ± 0.82 t C ha−1 y−1), tree mortality (1.0 ± 0.61 t C ha−1 y−1), aboveground detritus production (2.3 ± 0.39 t C ha−1 y−1) and belowground fine root production (1.8 ± 0.31 t C ha−1 y−1). Annual biomass increment was rather small because of high tree mortality during the 5 years. Total NPP at the site was
6.5 ± 1.07 t C ha−1 y−1, including the NPP of the forest floor community (1.1 ± 0.06 t C ha−1 y−1). The soil surface CO2 efflux (RS) was averaged across the 5 years of record using open-flow chambers. The mean estimated annual RS amounted to
7.1 ± 0.44 t C ha−1, and the decomposition of soil organic matter (SOM) was estimated at 3.9 ± 0.24 t C ha−1. RH was estimated at 4.4 ± 0.32 t C ha−1 y−1, which included decomposition of coarse woody debris. Biometric NEP in the forest was estimated at 2.1 ± 1.15 t C ha−1 y−1, which agreed well with the eddy-covariance based net ecosystem exchange (NEE). The contribution of woody increment (Δbiomass + mortality)
of the canopy trees to NEP was rather small, and thus the SOM pool played an important role in carbon storage in the temperate
forest. These results suggested that the dense forest floor of dwarf bamboo might have a critical role in soil carbon sequestration
in temperate East Asian deciduous forests. 相似文献
16.
Soil Nutrients Limit Fine Litter Production and Tree Growth in Mature Lowland Forest of Southwestern Borneo 总被引:1,自引:0,他引:1
Efforts to improve models of terrestrial productivity and to understand the function of tropical forests in global carbon
cycles require a mechanistic understanding of spatial variation in aboveground net primary productivity (ANPP) across tropical
landscapes. To help derive such an understanding for Borneo, we monitored aboveground fine litterfall, woody biomass increment
and ANPP (their sum) in mature forest over 29 months across a soil nutrient gradient in southwestern Kalimantan. In 30 (0.07 ha)
plots stratified throughout the watershed (∼340 ha, 8–190 m a.s.l.), we measured productivity and tested its relationship
with 27 soil parameters. ANPP across the study area was among the highest reported for mature lowland tropical forests. Aboveground
fine litterfall ranged from 5.1 to 11.0 Mg ha−1 year−1 and averaged 7.7 ± 0.4 (mean ± 95 C.I.). Woody biomass increment ranged from 5.8 to 23.6 Mg ha−1 year−1 and averaged 12.0 ± 2.0. Growth of large trees (≥60 cm dbh) contributed 38–82% of plot-wide biomass increment and explained
92% of variation among plots. ANPP, the sum of these parameters, ranged from 11.1 to 32.3 Mg ha−1 year−1 and averaged 19.7 ± 2.2. ANPP was weakly related to fine litterfall (r
2 = 0.176), but strongly related to growth of large trees at least 60 cm dbh (r
2 = 0.848). Adjusted ANPP after accounting for apparent “mature forest bias” in our sampling method was 17.5 ± 1.2 Mg ha−1 year−1.Relating productivity measures to soil parameters showed that spatial patterning in productivity was significantly related
to soil nutrients, especially phosphorus (P). Fine litterfall increased strongly with extractable P (r
2 = 0.646), but reached an asymptote at moderate P levels, whereas biomass increment (r
2 = 0.473) and ANPP (r
2 = 0.603) increased linearly across the gradient. Biomass increment of large trees was more frequently and strongly related to
nutrients than small trees, suggesting size dependency of tree growth on nutrients. Multiple linear regression confirmed the
leading importance of soil P, and identified Ca as a potential co-limiting factor. Our findings strongly suggest that (1)
soil nutrients, especially P, limit aboveground productivity in lowland Bornean forests, and (2) these forests play an important,
but changing role in carbon cycles, as canopy tree logging alters these terrestrial carbon sinks.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
17.
Altitudinal forest and climate changes from warm, dry valley bottom (1250 m a.s.l.) to cool, humid ridge top (3550 m a.s.l.) along the typical dry valley slopes of the Bhutan Himalaya were studied. Annual mean temperature decreased upslope with a lapse rate of 0.62 °C·100 m−1 from 18.2 °C at the valley bottom to 4.3 °C at the ridge top. On the contrary volumetric soil moisture content increased from 14.7 to 75.0%. This inverse relationship is the major determinant factor for the distribution of different forest types along the altitudinal gradient. Based on the quantitative vegetation data from 15 plots arranged ca. 200 m in altitude interval (1520–3370 m a.s.l.), a total of 83 tree species belonging to 35 families were recorded. Three major formation types of lower and upper coniferous forests, and a mid-altitude evergreen and deciduous broad-leaved forest were contrasted. Including two transitional types, five forest zones were categorized based on cluster analysis, and each zone can be characterized by the dominants and their phytogeographical traits, viz. (1) west Himalayan warm, dry pine (1520–1760 m a.s.l.), (2) wide ranging east-west Himalayan mixed broad-leaved (1860–2540 m a.s.l.), (3) humid east Himalayan evergreen broad-leaved (2640–2820 m a.s.l.), (4) cool, humid east Himalayan conifer (2950–3210 m a.s.l.), and (5) wide ranging cold, humid conifer (3305–3370 m a.s.l.). Structurally, total basal area (biomass) increased from 15.2 m2 ha−1 in the pine forest (1520 m) to 101.7 m2 ha−1, in the conifer forest (3370 m a.s.l.). Similarly, soil organic carbon increased from 2.7 to 11.3% and nitrogen from 0.2 to 1.9% indicating dry, poor nutrient fragile ecosystem at the dry valley bottom. We concluded that low soil moisture content (<20%) limits downslope extension of broad-leaved species below 1650 m a.s.l. while coldest month’s mean temperature of −1 °C restricted the upslope extension of evergreen broad-leaved species above 3000 m a.s.l. Along the dry valley slopes, the transition from dry pine forest in the valley bottom, to a mixture of dry west Himalayan evergreen and deciduous east Himalayan broad-leaved, and to humid evergreen oak–laurel forests feature a unique pattern of forest type distribution. 相似文献
18.
Salix gracilistyla is one of the dominant plants in the riparian vegetation of the upper-middle reaches of rivers in western Japan. This species
colonizes mainly sandy habitats, where soil nutrient levels are low, but shows high potential for production. We hypothesized
that S.␣gracilistyla uses nutrients conservatively within stands, showing a high resorption efficiency during leaf senescence. To test this hypothesis,
we examined seasonal changes in nitrogen (N) and phosphorus (P) concentrations in aboveground organs of S. gracilistyla stands on a fluvial bar in the Ohtagawa River, western Japan. The concentrations in leaves decreased from April to May as
leaves expanded. Thereafter, the concentrations showed little fluctuation until September. They declined considerably in autumn,
possibly owing to nutrient resorption. We converted the nutrient concentrations in each organ to nutrient amounts per stand
area on the basis of the biomass of each organ. The resorption efficiency of N and P in leaves during senescence were estimated
to be 44 and 46%, respectively. Annual net increments of N and P in aboveground organs, calculated by adding the amounts in
inflorescences and leaf litter to the annual increments in perennial organs, were estimated to be 9.9 g and 0.83 g m−2 year−1, respectively. The amounts released in leaf litter were 6.7 g N and 0.44 g P m−2. These values are comparable to or larger than those of other deciduous trees. We conclude that S. gracilistyla stands acquire large amounts of nutrients and release a large proportion in leaf litter. 相似文献
19.
Culm recruitment, standing crop biomass, net production and carbon flux were estimated in mature (5 years after last harvest)
and recently harvested bamboo (Dendrocalamus strictus (Roxb.) Nees) savanna sites in the dry tropics. During the 2 study years bamboo shoot recruitment was 1711–3182 and 1432–1510
shoots ha−1 in harvested and mature sites, respectively. Corresponding shoot mortality was 66–93% and 62–69%, respectively. Total biomass
was 34.9 t ha−1 at the harvested site and 47.4 t ha−1 at the mature site. Harvesting increased the relative contribution of belowground bamboo biomass. Annual litter input to
soil was 2.7 and 5.9 t ha−1 year−1 at the harvested and mature sites, respectively. The bulk of the annual litterfall (78–88%) occurred in the cool dry season
(November to February). The mean litter mass on the savanna floor ranged from 3.1 to 3.3 t ha−1; at the harvested site wood litter contributed 70% of the litter mass and at the mature site leaves formed 77% of the litter
mass. The mean total net production (TNP) for the two annual cycles was 15.8 t ha−1 year−1 at the harvested site and 19.3 t ha−1 year−1 at the mature site. Nearly half (46–57%) of the TNP was allocated to the belowground parts. Short lived components (leaves
and fine roots) contributed about four-fifths of the net production of bamboo. Total carbon storage in the system was 64.4
t ha−1 at the harvested site and 75.4 t ha−1 at the mature site, of which 23–28% was distributed in vegetation, 2% in litter and 70–75% in soil. Annual net carbon deposition
was 6.3 and 8.7 t ha−1 year−1 at harvested and mature sites, respectively. 相似文献
20.
The impact of extended herbicide (H) and annual fertilizer (F) treatments on the mineral soil carbon (C) pool and nitrogen
(N) and phosphorous (P) availability were analyzed in managed loblolly pine (Pinus taeda L.) plantations in the Piedmont of Georgia in stands ranging from 4 to 16 years old. Mineral soil C, N, P, and extractable
P were measured in 66 plots in three locations comparing H, F, and their combination HF to the Control plots. Soils were sampled
in January 2000 near Eatonton (n = 40), in August 2001 near Athens (n = 12), and in March 2003 near Dawsonville (n = 14). In addition, twelve plots (two H and two HF at each location) were measured on 17 dates using a mixed bead resin core
technique to estimate mineral soil N availability. At all three study locations the H treatment tended to deplete the mineral
soil C pool while, overall, the F treatments did not determine any significant mineral soil C increase. The soil C pool (0-
to 50-cm depth) was depleted by about 5 Mg C ha−1 under the H-treated plots near Eatonton. The HF plots had much higher resin-extractable N than the corresponding H plots
in all months of the year. At a plot level, HF values ranged from about 9 to 3,195 μg N g−1 resin while H values ranged from about 4 to 858 μg N g−1 resin. The corresponding annual cumulative resin-extractable N ranged from about 13 kg N ha−1 in the H to about 372 kg N ha−1 in the HF. Extractable P values were also elevated in all F-treated plots. Fertilization and herbicide treatments favored
C sequestration only in the aboveground biomass. No significant change was observed in the mineral soil C pool, despite the
generally observed increases in soil available N and P. 相似文献